Sound picture system



Sept. 5, 1933 a... A. ELMER 1,925,690

SOUND PICTURE SYSTEM Filed Nov. 5. 1931 FIG! 29 27 28 O '0 i a? 22 lNVENTOR LA. 6 LME R ATTORNEY Patented Sept. 5, 1933 UNITED STATES PATENT OFFICE SOUND PICTURE SYSTEM Lloyd A. Elmer, West @rarnge, N. .lL, assignor to Bell Telephone Laboratories, Incorporated, New York, N. TL, a corporation of New York Application November 5, 1921. Serial No. 573,121

3 @laims. (o1. Wit-23) This invention relates to sound picture appaerated by a member which is driven in unison ratus and more particularly to a control inechawith the sprocket. nism for maintaining a film at constant velocity In accordance with the invention the firm drivfor sound translation. ing sound sprocket is mounted on a shaft which 5 A well known type of apparatus of this charis driven through a resilient member by a gear acter in which sound and scene are synchrodrive. A circular frame also mounted on this nously recorded or reproduced involves driving shaft is arranged to drive a plurality of bellows the various mechanisms from a common source. pumps. Three pairs of bellows are mounted This includes an apparatus for intermittently within the circular frame and connected thereto.

positioning a film before lenses for photographic Each pair of bellows is filled with liquid and ar- 65 exposure or projection and a cylinder or sprocket ranged in such manner that the liquid may be wheel for moving the film before sound transpumped at a given rate alternately from one bellating apparatus. It is well established that the lows to the other. Each pair of bellows is a film must be moved at a uniform velocity for separate pumping unit connected in the center reproducing sound as well as for recording sound to a common supporting member which termi- 70 and that any velocity variations in either case nates in a shaft mounted eccentric to the outer that cause a pitch variation of over 0.3% will circular frame. The support for this shaft is introduce noticeable sound distortion. In some adjustable to obtain different eccentricities in cases a pitch variation of over 0.1% will introduce order to regulate the pumping action of the sound distortion. Consequently, it is a fundabellows.

mental requirement that the cylinder or sprocket As the circular frame is rotated with the sound which is used to move the film past the sound sprocket the bellows of each pair are alternately translating apparatus be rotated at an unvarying compressed and expanded causing a pumping velocity. action of the liquid. This pumping action pro- The intermittent motion and sprocket are orduces a force whose successive instantaneous dinarily driven by gears which are connected values if plotted between suitable coordinates, through shafts and other gears to an electric would generate a sine curve. This force will acmotor. The parts for this mechanical transmiscordingly be referred to hereinafter as a sinussion apparently cannot be produced and conoidal force. With several pairs of bellows equally nected together in a manner to eliminate all spaced angularly the resultant flow of liquid 85 irregularities of motion. Such irregularities have is constant for a constant velocity and an even a tendency to produce velocity variations at the load is thus placed upon the sound sprocket. sound sprocket. Irregularities in film load also This load is many times greater than the greathave a tendency to introduce velocity variations est load variation caused by film inequalities.

at the sound sprocket. The greatest variation This acts in the manner of a swamping load in film l ad iS probably produced when a film which minimizes the efiect of the tendency of Splice passes through the tension p ordinarily the film variations to cause velocity variations used at the point of sound translation. in the sound sprocket. Since the resistance to One method whichhas been used to minimize the flow of the liquid is proportional to the' vethe effect O irregularities in he driving mechalocity of rotation any tendency toward a sudden 5 n S is to mount a vy flywheel 0n the Sound increase or decrease in the velocity of rotation Sprocket Shafti functioning this flywheel would be practically annulled by the resulting is to absorb or give out mechanical energy 1n great increase or decrease respectively in reg pi tq ig g f EF ig g fi f g sistance. Consequently, irregularities in velocy mlmmlzmg e uc ua Ions as t ity produced in the driving, mechanism effect an be of large mass to reduce the effect of these disaction in the spiings or elastic member beturbances. The size, weight and momentum of th fi 1 d th 1 the flywheel are objectionable both in record- Ween 8 nvmg gear an e Clrcu ar ing and reproducing apparatus frame and do not noticeably affect the velocity of 50 The object of this invention is, therefore, to the Sound Sprocket provide in a sound picture apparatus a velocity 2 the drawing, 1 is avieW in elevation and regulator of light weight and negligible inertia p y in section f h v l i y regulator n arranged to dissipate energy proportional to the film driving sprocket; velocity of rotation of the film driving sprocket Fig. 2 is an end elevation of the bellows of the 55 comprising a plurality of pressure pumps opvelocity regulator; and

Fig. 3 illustrates a well known projector equipped with the velocity regulator.

In the illustrated embodiment Fig. 1, the shaft 10 interconnects a gear set driven by a motor with the final driving gear 12. The intermittent motion which is also connected to this gear set, is of conventional design. The intermittent motion and other operating parts of the projector are not shown in detail since they are all of conventional design and well understood. The driving gear 12 is associated with gear 13 for driving the sound sprocket 1 and circular frame 20. The gear 13 is rigidly connected to sleeve 14 which freely rotates on housing 5. The gear 13 and sleeve 14 are rigidly connected to the circular plate 16 which is connected to a plurality of springs 15. The opposite end of spring 15 is connected to the circular frame 20 by angle pieces 18 which are rigidly connected to frame 20 by rivets 19. Frame 20 is rigidly connected to shaft 4 by pin 6. The sprocket wheel 1 is also rigidly connected to shaft 4 by a key not shown. The sprocket 1 and frame 20 are thus driven by gear 12 under the control of an elastic member shown in the form of a plurality of springs.

In the cross-sectional view of the velocity regulator Fig. 1, the bellows 21 and 22 forming one pair of bellows are shown in cross section to illustrate the internal structure. This structure is used for each pair of bellows. Bellows 23 and 24 each form one half of a second and third pair of bellows. Each bellows is connected to frame 20 by an eyebolt such as shown at 27. This eyebolt may have slight movement with relation to its fastening bolt 28. The central portion of each bellows is connected to a common supporting member 35. This supporting member terminates in shaft 34 which is mounted eccentrically with relation to the circular frame 20. It is thus apparent that as the circular frame 20 rotates each bellows is alternately compressed and expanded. Each pair of bellows is filled with liquid, preferably oil. Each pair of bellows is interconnected by a tube 30 which extends through the supporting member 35. A valve 31 permits the regulation of the rate of flow from one bellows to the other of each pair. The

' eccentricity of shaft 34 may be regulated by an adjustment of mounting 36.

The film 2 and film pad 3 are of conventional designs. The film 2 ordinarily has both picture and sound records thereon and is drawn by sprocket 1 past thepoint .of sound translation after it has been carried before the picture lenses by an intermittent motion. As hereinbefore stated inequalities of the film 2 exert a varying load upon the sound sprocket 1. In order to minimize the effect of this variation in film load on the sound sprocket the resistance load exerted by the velocity regulator is made several hundred times greater than the load introduced by the greatest film variation. The bellows mounting shaft 34 may be fixed by adjustment to obtain the correct ratio between the film load and the velocity regulator load.

The arrangement proposed for the bellows 21 to 26, inclusive is best shown in Fig. 2. These bellows are arranged in such manner that .all bellows are constantly operated at an even rate to dissipate energy proportional to the velocity of rotation. The operation as described with the bellows arranged as shown causes a pumping action upon the liquid that is sinusoidal for each pair of bellows, each pump delivering a sinusoidal force 120 out of phase with each other pump.

A projector has been shown in Fig. 3 illustrating the velocity regulator associated therewith. The driving motor is shown at 50 connected by shaft 53 with the apparatus of the projector. The usual projector head is shown at 51 and the sound unit at 52. The circular frame 20is shown associated with the sound unit 52.

The velocity regulator may assume various forms other than the form shown. Various types of compression pumps may be used in place of the bellows. It is, therefore, not the intention to limit the invention to the particular form shown.

What is claimed is:

1. In a sound picture mechanism, a cylinder for imparting a uniform motion to a band of inconsiderable mass, a velocity regulator for said cylinder comprising a pumping device having a plurality of pairs of pumps, each pair arranged to deliver a sinusoidal force out of phase with respect to each other pair, and a common driving means for said cylinder and velocity regulator.

2. In a sound picture mechanism, a cylinder for imparting a uniform motion to a band of inconsiderable mass, a velocity regulator for said cylinder comprising a pumping device having a plurality of pairs of pumps, each pair arranged to deliver a sinusoidal force out of phase with respect to each other pair, a shaft for driving said cylinder and velocity regulator, and a driving means for said shaft.

3. In a sound picture mechanism, a cylinder for imparting a uniform motion to a band of inconsiderable mass, a velocity regulator arranged to dissipate energy proportional to the velocity of rotation of said cylinder comprising a pumping device having a plurality of pairs of pumps, each pair arranged to deliver a sinusoidal force out of phase with respect to each other pair and a common driving means for said cylinder and velocity regulator.

4. In a sound picture mechanism, a cylinder for imparting a uniform motion to a band of inconsiderable mass, a driving means and means to annul the effect of velocity variations of said cylinder due to irregularities of structure and load, comprising a pumping device operated by said driving means in unison with said cylinder and having a plurality of pairs of pumps, each pair arranged to deliver a sinusoidal force out of phase with respect to each other pair.

5. In a sound picture mechanism, a cylinder for imparting a uniform motion to a band of inconsiderable mass, a velocity regulator for said cylinder arranged to dissipate energy proportional to the velocity of rotation of said cylinder comprising a plurality of pairs of bellows filled with liquid, each pair being operable to alternately pump said liquid from one bellows to the other and each pair being arranged to deliver a sinusoidal force out of phase with the force delivered by each other pair of bellows and a common driving means for said cylinder and said velocity regulator.

6. In a sound picture mechanism, a cylinder for imparting a uniform motion to a band of inconsiderable mass, a velocity regulator for said cylinder for annulling velocity variations comprising a plurality of reciprocating pressure pumps, each pump arranged to deliver a sinusoidal force out of phase with respect to each other pump and a common driving means for said cylinder and velocity regulator.

7. In a sound picture mechanism, a cylinder for imparting a uniform motion to a band of inconsiderable mass, a velocity regulator for said cylinder for annulling velocity variations comprising a plurality of reciprocating pressure pumps, each pump arranged to deliver a sinusoidal force out of phase with respect to each other pump, a circular member for operating said pumps, a shaft, means for rigidly mounting said cylinder and circular member on said shaft and a driving means for said shaft.

8. In a sound picture mechanism, a cylinder for imparting a uniform motion to a band of inconsiderable mass, a velocity regulator for said cylinder for annulling velocity variations com- 

